There is no such thing as "being done" and certainly nowhere near 8 days as that is how long it takes the system just to adapt to fasting and the cleansing to begin eliminating the causative agents.
We are not little machines and there will not be some magical demarcation point and poof! You're clean. We spend a lifetime putting junk in our system plus envirmental pollution and you're simply not going to "be done" in one fell swoop. Even a 40 day fast is just a very good start. Cleansing is an ongoing process with many facets.
Fasting and the other cleanses are actully the easy part where everything is all worked out for and you don't hafta make daily decisions as to what to put in your system. The actual hard work comes after any of the cleanses in educating yourself on nutrition and be willing to experiment till you find your own groove and last but not least it also includes regular exercise.
Check out the FAQs at the top of the page a read a post called "Detox Stages" for some idea of the cleansing timeline when fasting.
You're not getting it. There is no "over ' there are no "signs". You're looking for some magical answer and there isn't one. As I suggested before look at the FAQs to the post "Detox Stages" for rough guide on the cleansing timeline and go for as long as you feel matches the goals you wish to achieve.